Active materials, electrodes, secondary batteries, battery packs, and vehicles

Abstract

To provide: an active material, capable of achieving a secondary battery excellent in rapid charge / discharge performance and cycle life performance; an electrode; a secondary battery; a battery pack; and a vehicle.SOLUTION: There is provided an active material including a composite oxide having a crystal structure including a rhenium oxide block structure that contains octahedral structures configured of oxygen and a metal element and that is configured by the octahedral structures sharing vertices. The composite oxide is represented by general formula LiaMbNbMocOd. Here, M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y and Si. In a micro-Raman spectrum with an excitation wavelength of 532 nm for the composite oxide, a difference between a shift amount S1 of a Raman peak P1 derived from Mo-O bonds at 640±10 cm-1 and a shift amount S2 of a Raman peak P2 derived from Nb-O bonds at 920±20 cm-1 is 285 cm-1 or more.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] Embodiments of the present invention relate to active materials, electrodes, secondary batteries, battery packs, and vehicles. [Background technology]

[0002] In recent years, research and development of secondary batteries, such as lithium-ion secondary batteries and non-aqueous electrolyte secondary batteries, has been actively pursued as high-energy-density batteries. Secondary batteries are expected to be used as power sources for vehicles such as hybrid and electric vehicles, as well as for uninterruptible power supplies in mobile phone base stations. Therefore, secondary batteries are required to have excellent performance in other areas as well as energy density, such as rapid charge / discharge performance and long-term reliability.

[0003] A common negative electrode in lithium-ion batteries is a carbon-based negative electrode that uses carbonaceous materials such as graphite as the active material. However, batteries using carbon-based negative electrodes were susceptible to internal short circuits, heat generation, and fire due to the deposition of metallic lithium dendrites on the electrode after repeated rapid charging and discharging. Therefore, batteries were developed that use metal composite oxides instead of carbonaceous materials for the negative electrode, thereby increasing the negative electrode operating potential. For example, spinel-type lithium titanium composite oxide (Li4Ti5O) 12 A battery using Li as the negative electrode has an average operating potential of 1.55V (vs. Li / Li + Because of its high potential, Li dendrite deposition does not progress, enabling stable rapid charging and discharging, and because it operates at a potential where reduction side reactions of the electrolyte are less likely to occur, it has a longer lifespan compared to batteries using carbon-based negative electrodes. However, Li4Ti5O 12 In batteries using carbon as the negative electrode, the theoretical capacity of the active material is low at 175 mAh / g, resulting in a lower energy density compared to batteries equipped with a carbon-based negative electrode.

[0004] Therefore, monoclinic titanium niobium oxide (TiNb2O7) is being investigated. Using the oxidation-reduction potential of lithium as a reference, 1V (vs.Li / Li) is considered. +This active material exhibits high capacity while having an operating potential in the vicinity of the 2000 ohm. For this reason, it is expected to achieve an energy density exceeding that of carbon-based anodes in terms of volumetric energy density. However, in order to fully popularize electric vehicles, it is desirable to further increase the energy density of lithium-ion secondary batteries from the perspective of improving driving range, and the development of even higher-capacity rapid-charging batteries is desired. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-99287 [Patent Document 2] Japanese Patent Publication No. 2021-061223 [Patent Document 3] International Publication No. 2019 / 234248 [Non-patent literature]

[0006] [Non-Patent Document 1] Nature, 559, 556-563 (2018) [Non-Patent Document 2] J. Mater. Chem. A, 2019, 7, 6522-6532 [Non-Patent Document 3] International Tables for Crystallography (2006). 1st online ed. Chester: International Union of Crystallography. [Non-Patent Document 4] "Practical Aspects of Powder X-ray Radiation Analysis," First Edition (2002), edited by the X-ray Radiation Analysis Research Group of the Japan Society for Analytical Chemistry, authored by Izumi Nakai and Fujio Izumi (Asakura Shoten). [Overview of the project] [Problems that the invention aims to solve]

[0007] An object of an embodiment is to provide an active material and an electrode capable of realizing a secondary battery excellent in rapid charge / discharge performance and cycle life performance, a secondary battery and a battery pack excellent in rapid charge / discharge performance and cycle life performance, and a vehicle equipped with the battery pack.

Means for Solving the Problems

[0008] According to an embodiment, an active material including a composite oxide having a crystal structure including an octahedral structure composed of oxygen and a metal element and including a block structure of a ruthenium oxide type in which the octahedral structures are connected by vertex sharing is provided. The composite oxide has a general formula Li a M b NbMo c O d where M is Ti, Zr, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, Cr, W, B, Mg, Al, Ca, Y, and Si, and is at least one selected from the group consisting thereof, 0 ≦ a ≦ b + 2 + 3c, 0 < b ≦ 1.5, 0 < c ≦ 0.5, and 2.33 ≦ d / (1 + b + c) ≦ 2.50. In the microscopic Raman spectrum of the composite oxide at an excitation wavelength of 532 nm, the difference between the shift amount S1 of the Raman peak P1 derived from the Mo-O bond at 640 ± 10 cm -1 and the shift amount S2 of the Raman peak P2 derived from the Nb-O bond at 920 ± 20 cm -1 is 285 cm -1 or more 294 cm -1 below is satisfied.

[0009] According to another embodiment, an electrode including the above active material is provided.

[0010] According to still another embodiment, a secondary battery including a positive electrode, a negative electrode, and an electrolyte is provided. The positive electrode or the negative electrode is the above electrode.

[0011] According to still another embodiment, a battery pack including the above secondary battery is provided.

[0012] Furthermore, according to the embodiment, a vehicle equipped with the above-mentioned battery pack is provided. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram showing an example of a crystal structure that may be contained in the composite oxide included in the active material according to this embodiment. [Figure 2] A schematic diagram showing another example of a crystal structure that the composite oxide contained in the active material according to the embodiment may contain. [Figure 3] A schematic cross-sectional view showing an example of a secondary battery according to this embodiment. [Figure 4] Figure 3 shows an enlarged cross-sectional view of section A of the secondary battery. [Figure 5] A schematic partial cutaway perspective view showing another example of a secondary battery according to the embodiment. [Figure 6] Figure 5 shows an enlarged cross-sectional view of section B of the secondary battery. [Figure 7] A schematic perspective view showing an example of a battery pack according to this embodiment. [Figure 8] An exploded perspective view schematically showing an example of a battery pack according to this embodiment. [Figure 9] A block diagram showing an example of the electrical circuit of the battery pack shown in Figure 8. [Figure 10] A partially transparent view schematically showing an example of a vehicle according to the embodiment. [Figure 11] A schematic diagram showing an example of a control system for the electrical system in a vehicle according to this embodiment. [Figure 12] A graph showing the Raman spectra obtained in Examples 1-3 and Comparative Example 1. [Modes for carrying out the invention]

[0014] To obtain high-capacity materials, it is desirable to select materials that provide a large amount of charge compensation during carrier ion (e.g., lithium ions) insertion. For this purpose, composite oxides containing the hexavalent element molybdenum (Mo) can be used as compounds with even higher capacities. However, there are no reports of battery materials using molybdenum-niobium composite oxide materials with a high molybdenum content.

[0015] The embodiments will be described below with reference to the drawings. In the following description, components that perform the same or similar functions will be given the same reference numerals throughout all drawings, and redundant descriptions will be omitted. Note that each figure is a schematic diagram intended to explain the embodiments and facilitate their understanding, and their shapes, dimensions, ratios, etc., may differ from those of the actual device. These can be appropriately modified in consideration of the following description and known technology.

[0016] (First Embodiment) According to the first embodiment, an active material is provided which includes a composite oxide having a crystalline structure. The crystalline structure includes a rhenium oxide-type block structure in which octahedral structures composed of oxygen and a metal element are formed by vertex sharing. The composite oxide has the general formula Li a M b NbMo c O d It is represented as follows: In the general formula, M is at least one selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si. Each subscript in the formula satisfies 0≦a≦b+2+3c, 0≦b≦1.5, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50, respectively. In the micro-Raman spectroscopy spectrum of the composite oxide at an excitation wavelength of 532 nm, among the Raman peaks originating from the bonding between oxygen and metal elements contained in the above crystal structure, 640±10 cm⁻¹ is observed. -1 The shift amount S1(cm) of Raman peak P1 originating from Mo-O bonds within the range -1 ) and 920±20 cm -1The shift amount S2(cm) of the Raman peak P2 originating from the Nb-O bond within the range -1 The difference S2-S1 is 285 cm -1 That's all. Furthermore, the above subscript b can be within the range of 0 ≤ b ≤ 1.4.

[0017] The active material in question may be an active material for batteries. For example, the active material may be an electrode active material used in the electrodes of secondary batteries such as lithium-ion batteries or non-aqueous electrolyte batteries. More specifically, the active material may be, for example, a negative electrode active material used in the negative electrode of a secondary battery.

[0018] The above general formula Li a M b NbMo c O d (Element M and each subscript are as described above; omitted below) By using a composite oxide as the electrode active material, which has a crystal structure including the rhenium oxide type block structure described above, and in the Raman spectrum, Raman peaks P1 and P2 satisfy the shift difference S2-S1, a secondary battery with excellent rapid charge / discharge performance and cycle life performance can be realized.

[0019] <Crystal structure> The composite oxide contained in the active material according to the first embodiment corresponds to a part of an oxide material having the structure of the Wadsley-Roth phase, which is a crystalline phase in oxide materials containing niobium. In the Wadsley-Roth phase, the ratio of oxygen O to metal element M in the composition is such that the number of oxygen atoms and the number of metal element atoms are A O and A M Therefore, 2.33 ≤ A O / A M It has been reported that crystal structures can exist in the range of ≤2.65. For example, in the case of TiNb2O7, A O / A M This results in the reduced crystal structure of =2.33.

[0020] Here, reduction means a low proportion of oxygen in the structure. The Wadsley-Roth phase has a crystal structure in which oxygen-metal octahedron vertex-sharing structures form rhenium oxide-type block structures, and these blocks share octahedron rhombuses or tetrahedra interspersed to share vertices, resulting in rhenium oxide-type blocks (ReO3-type blocks) being connected in two dimensions. The crystal structure on the reduction side has a structure in which the size of the rhenium oxide-type blocks is small. Although the rhenium oxide-type crystal structure has voids that can accommodate many Li atoms, due to its highly symmetrical crystal structure, it is difficult to change the bond length between the metal element and the oxygen element to resolve the charge repulsion when Li is inserted. For this reason, the rhenium oxide-type crystal structure can be said to be a structure in which Li insertion is constrained by the charge repulsion when Li is inserted. Here, the crystal structure on the reduction side is A O / A M As the size of the rhenium oxide-type blocks decreases, the number of oxygen atoms in the structure decreases, resulting in a smaller rhenium oxide-type block. As a result, when Li is inserted, a crystal structure can be formed that allows for volume expansion due to changes in the bond length between the metal element and the oxygen element. For this reason, by including a rhenium oxide-type crystal structure, a large number of Li insertions can be achieved because there are no constraints on the structural changes when Li is inserted, even while having a large void.

[0021] In the case of the composite oxide included in the active material according to the first embodiment, by adopting a reducing crystal structure such as TiNb2O7, it becomes possible to insert more lithium (Li) into the crystal structure, resulting in a crystal structure with a large reversible capacity. In other words, the crystal structure of such composite oxide is a reducing crystal structure belonging to the Wadsley-Roth phase, which consists of three elements including niobium, molybdenum, and the metallic element M.

[0022] General formula Li a M b NbMo c O d Figure 1 shows a schematic diagram of an example of a crystal structure that a composite oxide represented by can contain. In this example, the number of atoms of the metal element M included as a constituent element is A M Number of oxygen atoms A O The ratio of A O / A M This is a crystal structure where =2.50. Figure 1 shows the unit cell in the

[0001] direction as viewed along the c-axis. The space group notation for the crystal structure is I - It belongs to 4 and is assigned the space group number 82. The space group referred to here corresponds to the content of International Tables for Crystallography (Non-Patent Literature 3), specifically Vol. A: Space-group symmetry (2nd online edition (2016); ISBN: 978-0-470-97423-0, doi: 10.1107 / 97809553602060000114) of that document. However, the space groups are P4 (space group number 75), I4 (space group number 79), P - 4 (space group number 81), P42 / n (space group number 86), I4 / m (space group number 87), P4nc (space group number 104), P - 421c (space group number 114), P - I such as 4n2 (space group number 118) - It is also possible to explain this by attribution to a simple cubic lattice with a quadruple axis of symmetry or quadruple antiaxis similar to 4 (space group number 82), and this may change if the composition ratio deviates from the stoichiometric composition ratio due to adjustment, or if structural distortion occurs due to the coexistence of different phases. The crystal structure 10 contains octahedra 10a and tetrahedra 10b composed of metal element 18 and oxygen element 19, respectively. The octahedra 10a are connected to each other by sharing vertices to form rhenium oxide type blocks (ReO3 type blocks). The size of the block is 3 x 3 = 9 octahedra 10a. The 9-unit rhenium oxide type blocks form planes in the a-axis and b-axis directions by sharing edges of octahedra 10a or vertices of tetrahedra 10b. The crystal structure is formed when multiple planes containing these 9 octahedra 10a are connected on the c-axis side by sharing octahedral edges or tetrahedral vertices.

[0023] General formula Li a M b NbMo c O dFigure 2 shows a schematic diagram of another example of a crystal structure that may be contained in the composite oxide represented by . Figure 2 shows the structure as viewed from the stacking direction of the ReO3 blocks. The ReO3 blocks enclosed by thick lines (e.g., block 15a) and the ReO3 blocks shown only by thin lines (e.g., block 15d) differ in the plane on which the metal element 18 is arranged. This example is characterized by the absence of structural periodicity. Blocks of different sizes are connected and exist according to the arrangement scheme of the Wadsley-Roth phase. The sides of the blocks range from 2 for the smallest to 6 for the largest. For example, block 15a consists of 3x3 octahedrons 11a, block 15b consists of 2x3 octahedrons 11a, block 15c consists of 2x4 octahedrons 11a, block 15d consists of 2x2 octahedrons 11a, block 15e consists of 3x6 octahedrons 11a, block 15f consists of 5x3 octahedrons 11a, and block 15g consists of 4x4 octahedrons 11a. These sizes can be freely adjusted according to the metal / oxygen ratio due to the mixture of elements M, Nb, and Mo, and are not limited. The majority are connected by octahedron edge sharing 17, but some may also include tetrahedron vertex sharing by tetrahedrons 11b. Compared to Figure 1, there are fewer tetrahedrons, and the number of octahedron edge sharing increases as tetrahedron vertex connections are replaced by octahedron edge connections, thus increasing octahedron lattice distortion. The large lattice distortion of the octahedron facilitates structural relaxation through changes in bond length during Li insertion, making it possible to increase the amount of Li inserted. Furthermore, because the octahedral edge sharing is included without a periodic structure, the asymmetry of the skeleton is maintained even when the amount of Li inserted is increased. Therefore, the crystal structure in Figure 2 has an even greater reversible capacity than the crystal structure in Figure 1. For this reason, by including the crystal structure in Figure 2 in the active material, it is possible to improve the capacity as well.

[0024] In the crystal structure shown in Figure 2, the metal / oxygen ratio, which changes with the composition ratio, can be adjusted by changing the size of the ReO3 type block and the number of connections shared by octahedron edges and tetrahedron vertices. Therefore, the oxygen / metal ratio can be changed by the composition ratio, and the general formula Li a M b NbMoc O d It is possible to freely adjust the composition within that range.

[0025] Molybdenum (Mo) can be incorporated into the crystal structure not only in a hexavalent state but also in a tetravalent or pentavalent state. The valency of Mo is determined by adjusting the charge balance according to the amount of other metal elements and oxygen present in the crystal structure shown in Figure 1 or Figure 2. In the case of a hexavalent element, the charge compensation during Li insertion with M elements such as Ti becomes a 3-electron reaction, thus increasing the theoretical capacity of insertable Li. Elements in a tetravalent or pentavalent state are arranged in the crystal structure in such a way that electrons are supplied to the d-band of the Mo element. Therefore, by including tetravalent or pentavalent Mo, the conductivity can be changed and battery performance can be improved. It is known that the Wadsley-Roth phase containing molybdenum has a high operating potential (becomes noble). Comparing oxides containing titanium and niobium, for example, in a titanium-niobium-molybdenum composite oxide, which is one embodiment of the first embodiment, the operating potential can be increased compared to TiNb2O7 by having a crystal structure containing a high concentration of molybdenum. Therefore, the operating potential falls within a range where reduction side reactions of the electrolyte are minimal, resulting in a long lifespan.

[0026] In the active material in question, the cycle life performance is improved due to the formation of Schottky defects. In Schottky defects, not only is there a vacancy for oxygen, but Mo is also lost to adjust the charge balance, forming a vacancy. When Li is inserted, the defect areas within the material have less charge repulsion, making it easier to capture Li. As a result, some Li remains in the active material without being desorbed during discharge. This effect suppresses the decrease in electronic conductivity after Li desorption, and thus makes it possible to maintain the electronic conductivity paths within and between the secondary particles of the active material when Li desorption and insertion are repeated. As a result, the cycle life performance of the electrode can be improved.

[0027] Due to the effects described above, the formation of defects improves the electronic conductivity of the active material, thereby improving battery performance. On the other hand, if there are too many defects, the trapped Li will inhibit internal diffusion, so the charge and discharge rate cannot be increased indefinitely.

[0028] General formula Li a M b NbMo c O d In this diagram, the subscript d reflects the amount of oxygen vacancies.

[0029] In the active material, the introduction of defects alters the molecular vibrations originating from the Mo-O bond. Therefore, it is possible to quantitatively evaluate defects by micro-Raman spectroscopy. Specifically, in micro-Raman spectroscopy of the active material using an excitation wavelength of 532 nm, the shift amount S1 (cm) of the Raman peak P1 originating from the Mo-O bond, among the Raman peaks resulting from the bond between the transition metal and oxygen originating from the crystal structure, is measured. -1 ) and the shift amount S2 (cm) of the Raman peak P2 originating from the Nb-O bond. -1 The difference S2-S1 is 285 cm -1 That concludes the report. The Raman peak P1 shows a peak originating from an octahedral bond containing the element Mo. The shift amount S1 indicates the peak top position of Raman peak P1, which is 640 ± 10 cm. -1 It is within the range. The Raman peak P2 shows a peak originating from the bonding of vertex-shared Nb-O octahedra. The shift amount S2 indicates the peak top position of Raman peak P2, which is 920 ± 20 cm. -1 It is within the range. Due to the Mo deficiency, the Raman peak P1 shifts to a lower energy side. The Raman peak P1 shifts 285 cm below the Raman peak P2. -1 By using an active material that exhibits the above-mentioned shifted state, the effects described above can be achieved. A larger shift difference S2-S1 indicates a larger number of defects. Considering the rapid charge / discharge performance, 290 cm⁻¹ -1 The following shift difference S2-S1 is preferred. For micro-Raman spectroscopy measurements, for example, the method described later is used.

[0030] General formula Li a M b NbMo c O d In addition to the Nb element and the Mo element as metal elements, the composite oxide represented by can further contain an element M different from them. In the case of the structure in FIG. 2, the structure can be maintained by connecting the change in the oxygen / metal composition ratio due to charge compensation to the change in the size of the ReO3-type block and the change in the octahedral edge sharing and tetrahedral vertex sharing at the connection part. The Mo element can be included in the structure by adjusting the valence in the range of tetravalent to hexavalent in the structure. Further, such an active material can easily create Schottky-type defects in the structure as described above. Therefore, the degree of freedom in adjusting the charge balance in the structure is high, and thereby the element M can be freely selected. As the M element, at least one can be selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, Zr, and Si. In the above general formula, the subscript b can satisfy, for example, 0 < b.

[0031] The above M element can be included in the crystal structure, for example, as a metal element constituting the above-described tetrahedron or octahedron. Further, the M element can exist in the active material in a form not included in the crystal structure of the composite oxide.

[0032] For example, the elements vanadium (V) and phosphorus (P) can be included in the crystal structure as pentavalent elements. Titanium (Ti), zirconium(Zr) and silicon (Si) can be included in the structure as tetravalent elements. Iron (Fe), chromium (Cr), aluminum (Al), bismuth (Bi), antimony (Sb), boron (B), arsenic (As), cobalt (Co), manganese (Mn), nickel (Ni), and yttrium (Y) can be incorporated into the crystal structure as trivalent elements. Magnesium (Mg) and calcium (Ca) can be incorporated into the crystal structure as divalent elements. Potassium (K) and sodium (Na) can be incorporated into the crystal structure as monovalent elements. Of these elements, tetravalent elements are preferred because their charge is higher than that of elements with three or fewer valencies, allowing for greater inclusion without reducing the oxygen / metal ratio in the structure and increasing the Mo ratio in the structure. In particular, titanium (Ti) is the element that can be included in the largest quantity in the structure, and its ionic radius is close to that of pentavalent Nb, making it easy to incorporate into the structure, and it is the most preferred of the M elements.

[0033] Tantalum (Ta) can substitute for the element Nb as a pentavalent element. Since Ta and Nb belong to the same group in the periodic table, their physical and chemical properties are similar. Therefore, it is possible to obtain equivalent battery performance by substituting Nb with Ta.

[0034] Tungsten (W), as a hexavalent element, can replace some of the Mo elements. Generally, Wadsley-Roth phases containing W are known to have high rate performance due to the rapid Li diffusion rate within the solid. Therefore, the inclusion of W is considered to be able to further enhance the rate performance of the active material.

[0035] <Active material particles> The active material according to the first embodiment may take the form of particles, for example. That is, such an active material may have the general formula Li a M b NbMo c O dIt is represented as and may consist of particles of a composite oxide containing the crystalline structure described above. The active material may be a single primary particle, a secondary particle formed by the aggregation of multiple primary particles, or a mixture thereof.

[0036] The average primary particle diameter of the active material is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. When the average primary particle diameter of the active material is small, the diffusion distance of lithium ions within the primary particles is short, which tends to increase lithium ion diffusivity. Also, when the average primary particle diameter of the active material is small, the reaction area increases, which increases the reactivity between the active material and lithium ions, and tends to improve the lithium ion insertion and deinsertion reaction.

[0037] The average secondary particle diameter of the active material is preferably between 1 μm and 50 μm. By setting the average secondary particle diameter of the active material within this range, productivity during electrode manufacturing can be improved, and batteries with good performance can be obtained. This average secondary particle diameter refers to the particle size at which the integrated volume value in the particle size distribution determined by a laser diffraction particle size distribution analyzer becomes 50%.

[0038] The BET specific surface area of ​​the active material is 3.0 m². 2 / g or more 120m 2 It is preferable that the value be less than or equal to 4.0m 2 / g or more 110m 2 It is more desirable that the value be less than or equal to / g. Using an active material with a high specific surface area can improve the discharge rate performance of the battery. On the other hand, using an active material with a low specific surface area can improve the battery's lifespan and, in the electrode manufacturing process described later in the second embodiment, improve the coating properties of the slurry containing the active material.

[0039] The BET specific surface area refers to the specific surface area calculated using the nitrogen BET (Brunauer, Emmet, and Teller) method. The method for calculating the specific surface area based on this nitrogen BET method will be described in detail later.

[0040] <Manufacturing method> The active material according to the first embodiment can be manufactured as follows.

[0041] (Liquid-phase synthesis) The production of composite oxides is not particularly limited, but they can be synthesized by methods such as solid-phase reaction, sol-gel reaction, and hydrothermal synthesis. As an example, the production method of titanium-niobium-molybdenum composite oxide (i.e., element M=Ti) using the sol-gel reaction is described below.

[0042] Titanium compounds, niobium compounds, and molybdenum compounds are used as starting materials. Examples of titanium compounds include titanium tetraisopropoxide, titanyl sulfate, titanium chloride, ammonium titanium oxalate and its hydrate, titanium hydroxide, and titanium oxide. Examples of niobium compounds include niobium chloride, ammonium niobium oxalate and its hydrate, niobium hydroxide, and niobium oxide. Examples of molybdenum compounds include molybdenum chloride, ammonium molybdate and its hydrate, molybdenum hydroxide, and molybdenum oxide. When selecting an element other than Ti as element M, or when selecting another element together with Ti, the above titanium compounds are appropriately replaced or used in combination with compounds containing the selected element M.

[0043] It is preferable to dissolve the starting materials in pure water or acid beforehand to prepare a solution. By dissolving the materials, it is possible to obtain a dry gel in which each element is homogeneously mixed, thereby increasing reactivity. If the materials cannot be dissolved in pure water, dissolution can be carried out using an acid.

[0044] Examples of acids used to dissolve the raw materials include citric acid and oxalic acid, but oxalic acid is preferred from the viewpoint of solubility. For example, when using oxalic acid, a concentration of 0.5 M to 1 M is preferred. When dissolving, a temperature of 70°C or higher is preferred to shorten the reaction time.

[0045] If dissolving the raw materials is difficult, the reaction can be carried out using a dispersion. In this case, the average particle size of the raw materials contained in the dispersion should be 3 μm or less, more preferably 1 μm. After preparing a solution (or dispersion) of each compound adjusted to a predetermined composition ratio, the solution is heated and stirred while neutralizing it with an aqueous ammonia solution to adjust the pH. A gel solution is obtained by adjusting the pH. By setting the pH to 5 or higher and 8 or lower, it is possible to form a gel that homogeneously contains each raw material, thereby obtaining a dry gel with good reactivity during firing.

[0046] Next, the gel solution is heated to near its boiling point to evaporate the water and allow gelation to proceed. After gelation, the water is further evaporated to dry the gel and obtain a dry gel. During gelation and drying, for example, the entire solution can be evaporated and concentrated to obtain a dry gel. The dry gel produced by evaporating and concentrating the entire solution is preferably pulverized before calcination to reduce the average particle size to 10 μm or less, more preferably 5 μm or less. This reduces the particle size after calcination. The obtained dry gel is then calcined.

[0047] In the process of evaporating the solvent to obtain gel and dried gel, it is more preferable to use a spray dryer. By spraying, it is possible to form fine droplets of the sol solution. By drying in the state of fine droplets, it is possible to prevent particle aggregation that occurs during solvent drying, thereby making the particle size after drying smaller and reducing the amount of coarse particles. This improves the homogeneity of the reaction during calcination of the precursor and also suppresses particle aggregation during calcination. The drying temperature during spray drying is preferably between 100°C and 200°C.

[0048] When firing the dried gel, a pre-firing is performed at a temperature between 200°C and 500°C for a firing time between 1 hour and 10 hours. This allows for the removal of excess organic components, thereby increasing the reactivity during the main firing.

[0049] The firing process is preferably carried out at a firing temperature of 700°C to 900°C for a firing time of 1 hour to 10 hours. By firing within this temperature range, it is possible to obtain the desired phase and introduce the aforementioned defects in appropriate amounts. The higher the firing temperature, the greater the tendency for the amount of defects to increase.

[0050] The powder after calcination may have a high average particle size due to the formation of aggregates. In this case, it is preferable to adjust the desired average particle size by grinding.

[0051] The surface of the powder after mechanical grinding may change to an amorphous state. In this case, when used as an active material for batteries, it may generate an overvoltage during Li insertion and removal, potentially increasing side reactions. For this reason, it is preferable to perform annealing again. The annealing temperature should be below the main firing temperature, preferably between 500°C and 800°C.

[0052] <Various measurement methods> The following describes the measurement methods for the active material. Specifically, it explains the confirmation of the complex oxide, the measurement of the average particle size of the active material particles, and the measurement of the specific surface area of ​​the active material.

[0053] When using the active material contained in the electrodes of a battery as a sample, prepare the sample for measurement by performing the following pretreatment: First, completely discharge the battery. Next, disassemble the battery in a glove box under an argon atmosphere and remove the electrodes. Then, wash the removed electrodes with a solvent such as ethyl methyl carbonate. Further processing is performed for each measurement to prepare a sample in the appropriate form.

[0054] (Confirmation of complex oxides) The active material has the crystal structure described above, and the general formula Li a M b NbMo c O dThe presence of the composite oxide represented by can be confirmed by a combination of wide-angle X-ray diffraction (XRD), high-angle annular dark-field (HAADF), inductively coupled plasma (ICP) emission spectrometry, and inert gas dissolution-infrared absorption spectroscopy. The crystal structure can be determined by wide-angle XRD and HAADF, and the elemental composition can be determined by ICP emission spectrometry and inert gas dissolution-infrared absorption spectroscopy. The valence of elements can be measured, for example, by photoelectron spectroscopy (XPS) using characteristic X-rays.

[0055] XRD measurement is performed as follows: First, the active material particles are thoroughly pulverized to obtain a powder sample. The average particle size of the powder sample is preferably 20 μm or less. This average particle size can be determined using a laser diffraction particle size distribution analyzer.

[0056] Next, the powdered sample is filled into the holder portion of the glass sample plate, and its surface is made flat. For example, a glass sample plate with a holder portion depth of 0.2 mm can be used.

[0057] Next, the glass sample plate is placed in a powder X-ray diffractometer, and the XRD spectrum is measured using Cu-Kα rays. Specific measurement conditions are, for example, as follows: X-ray diffractometer: SmartLab manufactured by Rigaku Corporation X-ray source: CuKα ray Output: 40kV, 200mA Package measurement name: General-purpose measurement (concentrated method) Incident parallel slit opening angle: 5° Incident longitudinal limiting slit length: 10 mm Photodetector PSA: None Light-receiving parallel slit aperture angle: 5° Monochromatic method: Kβ filter method Measurement mode: Continuous Entrance slit width: 0.5° Light-receiving slit width: 20mm Measurement range (2θ): 5~70° Sampling width (2θ): 0.01° Scan speed: 1° ~ 20° / min.

[0058] In this way, an XRD spectrum relating to the active material is obtained. In this XRD spectrum, the horizontal axis represents the angle of incidence (2θ), and the vertical axis represents the diffraction intensity (cps). The scan speed can be adjusted within a range such that the count of the main peak in the XRD spectrum is between 50,000 and 150,000 counts.

[0059] When using the active material contained in the battery electrodes as a sample, the washed electrodes obtained after the above-described pretreatment are cut to an area approximately the same as the area of ​​the glass sample plate holder, and used as the measurement sample.

[0060] Next, the obtained sample is directly attached to a glass holder and XRD measurement is performed. XRD is used to measure materials other than the active material that may be contained in the electrode, such as the current collector, conductive agent, and binder, and the XRD patterns derived from these materials are identified. Then, if there are overlapping peaks in the sample that are thought to be derived from the active material and peaks of other materials, the peaks of materials other than the active material are separated. In this way, the XRD spectrum related to the active material is obtained.

[0061] To more precisely confirm whether the crystal structure of the measured sample belongs to the tetragonal crystal structure shown in Figure 1 above, the Rietveld method is used. For example, RIETAN-FP is used as the analysis program, and the confidence factor R is used. wpThis can be confirmed by verifying that the value is at least 20% or less, more preferably 15% or less. At this time, if there are peaks containing impurities and they overlap with the phase to be analyzed, the accuracy of the analysis may deteriorate. In this case, it is preferable to perform the analysis by excluding the areas that clearly overlap with peaks derived from impurities from the analysis range. However, this does not apply when the sample contains materials other than the active material according to the first embodiment, when the orientation of the sample is extremely high, or when coarse particles are mixed in, as the intensity ratio changes. In such cases, the structure should be confirmed by verifying that there are no inconsistencies in the position and relative intensity of all peaks attributed to the crystal structure. Also, when the spectral intensity is low and the background intensity is low, R wp The value may be small, and the confidence factor is not meaningful in its absolute value, but rather in relatively judging the goodness of fitting under certain measurement conditions.

[0062] The analysis method using RIETAN-FP is described in detail, for example, in Chapter 9, "Let's try using RIETAN-FP," of Non-Patent Literature 4 ("Practical Aspects of Powder X-ray Analysis," 1st edition (2002), edited by the X-ray Analysis Research Group of the Japan Society for Analytical Chemistry, edited by Izumi Nakai and Fujio Izumi (Asakura Shoten)).

[0063] RIETAN-FP is a Rietveld analysis program that is distributed free of charge (as of August 2022) on the developer's website (http: / / fujioizumi.verse.jp / ).

[0064] The structure shown in Figure 2 is difficult to analyze by XRD measurement because it does not exhibit structural periodicity. To confirm the structure shown in Figure 2, it is preferable to directly observe the microstructure. Observation can be performed using the High Angle Annular Dark-Field (HAADF) method with a Scanning Transmission Electron Microscope (STEM). From the viewpoint of improving measurement resolution, it is preferable to use spherical aberration correction. By obtaining an atomic image (10 nm × 10 nm) from a direction perpendicular to the ReO3 type block and confirming the positional relationship of the metal elements constituting the ReO3 block, the structure can be confirmed.

[0065] The content of each element in the active material particles contained in the sample can be determined for metallic elements by ICP emission spectrometry. While the element O can be quantified by methods such as inert gas dissolution-infrared absorption spectroscopy, precise quantification is difficult.

[0066] The active material particles contained in the electrodes undergo the following further processing after the pretreatment described above. The active material-containing component (for example, the active material-containing layer described in the second embodiment) is peeled off from the electrode's current collector, for example. The peeled portion is heated briefly in the air (about 1 hour at 500°C) to burn off unwanted components such as binder and carbon. Subsequently, the content of each element can be quantified by performing ICP emission spectrometry or the like.

[0067] The valency of metal elements contained in composite oxides can be measured using XPS as follows. It is preferable to use hard X-rays for the measurement because they have a deep detection depth and can measure a state closer to the bulk material. Spectroscopic techniques using hard X-rays are also called HAXPES. The valency can be determined by confirming the bond energy position in the narrow spectrum of each element. For example, for the element Ti, Ti2p 3 / 2A tetravalent peak derived from [the relevant element] is observed at 459.0 ± 0.4 eV. For the Mo element, the hexavalent peak derived from Mo3d 5 / 2 is observed at 232.2 ± 0.4 eV. For the Nb element, the pentavalent peak derived from Nb3d 5 / 2 is observed at 207.5 ± 0.4 eV. When low-valence elements are included, it can be discriminated by detecting a peak at an energy position lower than the previous valence. In particular, the Mo element may contain valences of pentavalent or less.

[0068] Sample measurement is performed non-destructively so that the element valence does not change. Therefore, for the measurement of the composite oxide contained in the electrode, the electrode is used as the sample without performing material extraction. Measurement is performed while paying attention not to let charge-up during sample measurement affect the peak position. In order to prevent peak shift due to charge-up, it is preferable to measure the electrode in a fully discharged state. If the electrode contains a conductive agent, charge-up can be reduced. Pay attention also because long-term X-ray irradiation can change the element valence by damaging the sample. Also, when materials with different structures are mixed, the peak may shift due to changes in the bonding state, so pay attention not to confuse it with valence changes. When elements with different valences are mixed, that is, when spectra are mixed with multiple peaks, the spectra can be separated by least-squares fitting, and the mixing ratio can be estimated from the area ratio of the separated peaks.

[0069] Note that the content ratio of Li represented by subscript a in the general formula Li a M b NbMo c O d changes according to the charge state of the electrode in which the composite oxide is used as the active material. For example, in the composite oxide contained in the negative electrode, Li is inserted as the battery is charged and the subscript a increases, and Li desorbs as the battery is discharged and the subscript a decreases.

[0070] (Raman spectroscopy measurement) A method for quantitatively evaluating the crystallinity of complex oxides contained in active materials is to perform measurements using a micro-Raman detector. For example, the LabRAM HR Evolution manufactured by Horiba, Ltd. can be used as a micro-Raman detector. The wavelength of the measurement light source is 532 nm. The measurement conditions are selected so that the ratio of peak height (Signal=S) to noise (Noise=N) on the spectrum (S / N ratio) and fluorescence scattering intensity do not affect the calculation of the measurement intensity. For example, the measurement conditions can be a slit size of 25 μm, laser intensity of 25%, objective lens of 100x, grating of 1800 gr / mm, exposure time of 10 s, and number of integrations of 5.

[0071] The intensity is calculated by fitting the measured spectrum. The measurement software, for example, LabSpec6, performs baseline correction and then least-squares fitting using the Gaussian-Lorentz function to determine the Raman shift (cm) of the corresponding peak. -1 It is preferable to calculate ).

[0072] Raman spectroscopy can be performed, for example, by the procedure described below.

[0073] If the active material is in powder form, it can be evaluated directly. However, when evaluating battery active material incorporated into a battery, the above-mentioned pretreatment is performed up to the cleaning of the electrodes, the active material is detached from the cleaned electrodes, and a sample is taken.

[0074] Using the collected sample, Raman spectroscopy measurements are performed, for example, under the conditions described earlier.

[0075] When performing measurements, use a standard Si sample and perform calibration of the intensity and Raman shift according to the instrument's recommended method before measurement. When measuring powders, place the powder on a glass slide. It is preferable to flatten the slide to reduce irregularities in order to facilitate focusing. When measuring powders containing binders or conductive components in electrodes, be aware of the presence or absence of Raman activity and the peak positions of other components contained in the mixture, such as the current collector, conductive agent, and binder. If they overlap, separate the peaks related to components other than the active material.

[0076] (Measurement of average particle size) The average primary particle size of the active material can be determined by observation using a scanning electron microscope (SEM). Specifically, the average primary particle size obtained by SEM observation can be calculated using the following method.

[0077] First, the lengths of the longest axis and the shortest axis of the primary particles obtained from SEM observation are measured, and the arithmetic mean of these lengths is defined as the primary particle diameter. This primary particle diameter measurement is performed on 100 randomly selected particles, and the average of these measurements is defined as the average primary particle diameter.

[0078] The average secondary particle diameter of the active material can be determined from the particle size distribution measured using a laser diffraction particle size distribution analyzer. For this particle size distribution measurement, a dispersion of the active material diluted with N-methyl-2-pyrrolidone to a concentration of 0.1% to 1% by mass is used as the sample. The particle size at which the integrated volume value in the obtained particle size distribution reaches 50% is defined as the average secondary particle diameter.

[0079] (Measurement of BET specific surface area) The BET specific surface area of ​​active material particles can be determined by the following method.

[0080] First, 4 g of active material is taken as a sample. Next, the evaluation cell of the measuring device is degassed by vacuum drying at a temperature of 100°C or higher for 15 hours. For example, a 1 / 2 inch evaluation cell can be used. Next, the sample is placed in the measuring device. For example, the Shimadzu-Micromerities Tristar II 3020 can be used as the measuring device. Next, in nitrogen gas at 77 K (the boiling point of nitrogen), the nitrogen gas adsorption amount (mL / g) of the sample is measured at each pressure P while gradually increasing the nitrogen gas pressure P (mmHg). Next, the adsorption isotherm is obtained by plotting the nitrogen gas adsorption amount for each relative pressure P / P0, using the value obtained by dividing the pressure P (mmHg) by the saturated vapor pressure P0 (mmHg) of the nitrogen gas as the relative pressure P / P0. Next, a BET plot is calculated from this nitrogen adsorption isotherm and the BET formula, and the specific surface area is obtained using this BET plot. The BET plot is calculated using the BET multipoint method.

[0081] The active material according to the first embodiment has a crystalline structure including a rhenium oxide type block structure, and its general formula is Li a M b NbMo c O d This includes a complex oxide represented by the formula. The rhenium oxide-type block structure is composed of octahedral structures with shared vertices, each composed of oxygen and a metal element. In the above general formula, M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si. The subscripts a, b, c, and d are numbers satisfying 0≦a≦b+2+3c, 0≦b≦1.5, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50. In the micro-Raman spectroscopy spectrum of the complex oxide at an excitation wavelength of 532 nm, there is a difference of 285 cm between the Raman shift amount S1 of the Raman peak P1 originating from the Mo-O bond and the Raman shift amount S2 of the Raman peak P2 originating from the Nb-O bond. -1There is such a difference. The electrode using the above composite oxide as the electrode active material exhibits excellent rapid charge-discharge performance and cycle life performance. Also, the secondary battery and battery pack using the above composite oxide as the electrode active material exhibit excellent rapid charge-discharge performance and cycle life performance. That is, such an active material is excellent in rapid charge-discharge performance and cycle life performance.

[0082] (Second Embodiment) According to the second embodiment, an electrode is provided.

[0083] The electrode according to the second embodiment includes the active material according to the first embodiment. This electrode can be a battery electrode including the active material according to the first embodiment as a battery active material. The electrode as a battery electrode can be, for example, a negative electrode including the active material according to the first embodiment as a negative electrode active material. Alternatively, the electrode can be a positive electrode including the active material according to the first embodiment as a positive electrode active material.

[0084] Such an electrode can include a current collector and an active material-containing layer. The active material-containing layer can be formed on one or both sides of the current collector. The active material-containing layer can include an active material, and optionally a conductive agent and a binder.

[0085] The active material-containing layer may contain the active material according to the first embodiment alone, or may contain two or more kinds of the active materials according to the first embodiment. Further, it may contain a mixture in which one or two or more kinds of the active materials according to the first embodiment are mixed with one or two or more other active materials. It is desirable that the content ratio of the active material according to the first embodiment to the total mass of the active material according to the first embodiment and other active materials is 10% by mass or more and 100% by mass or less.

[0086] For example, when the active material according to the first embodiment is included as a negative electrode active material, examples of other active materials include lithium titanate having a lamellar structure (for example, Li 2+x Ti3O7, 0 ≦ x ≦ 3), lithium titanate having a spinel structure (for example, Li 4+x Ti5O 12Examples include titanium dioxide (TiO2), anatase-type titanium dioxide, rutile-type titanium dioxide, niobium pentoxide (Nb2O5), hollandite-type titanium composite oxides, orthorhombic titanium composite oxides, and monoclinic niobium titanium oxide, niobium oxide, niobium titanium oxide, niobium molybdenum composite oxide, and niobium tungsten composite oxide.

[0087] As an example of the above orthorhombic titanium-containing composite oxide, Li 2+e M I 2-f Ti 6-g M II h O 14+σ Examples of compounds represented by are given. Here, M I It is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb, and K. II is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. In the composition formula, each subscript has the following properties: 0≦e≦6, 0≦f<2, 0≦g<6, 0≦h<6, -0.5≦σ≦0.5. As a specific example of an orthorhombic titanium-containing composite oxide, Li 2+e Na2Li6O 14 (0 ≤ e ≤ 6) is one example.

[0088] As an example of the above monoclinic type niobium titanium oxide, Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ Examples of compounds represented by the formula are: Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. The subscripts in the compositional formula are 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3. A specific example of monoclinic niobium titanium oxide is Li x Nb2TiO7 (0≦x≦5) is one example.

[0089] Another example of monoclinic niobium titanium oxide is Li x Ti 1-y M3 y+z Nb 2-z O 7-δ A compound represented by the formula is shown below. Here, M3 is at least one selected from the group consisting of Mg, Fe, Ni, Co, W, Ta, and Mo. The subscripts in the empirical formula represent 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0090] Conductive agents are added to enhance current collection performance and reduce contact resistance between the active material and the current collector. Examples of conductive agents include carbonaceous materials such as vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, graphite, carbon nanotubes, and carbon nanofibers. One of these may be used as a conductive agent, or two or more may be used in combination. Alternatively, instead of using a conductive agent, a carbon coating or an electronically conductive inorganic material coating may be applied to the surface of the active material particles. Furthermore, the current collection performance of the active material-containing layer can be improved by using a conductive agent and coating the surface of the active material with carbon or a conductive material.

[0091] A binder is added to fill the gaps between dispersed active materials and to bond the active materials to the current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as a binder, or two or more may be used in combination.

[0092] The mixing ratios of the active material, conductive agent, and binder in the active material-containing layer can be appropriately changed depending on the application of the electrode. For example, when the electrode is used as the negative electrode of a secondary battery, it is preferable to mix the active material (negative electrode active material), conductive agent, and binder in the following proportions: 68% to 96% by mass, 2% to 30% by mass, and 2% to 30% by mass, respectively. By setting the amount of conductive agent to 2% by mass or more, the current collection performance of the active material-containing layer can be improved. Furthermore, by setting the amount of binder to 2% by mass or more, sufficient bonding between the active material-containing layer and the current collector can be achieved, and excellent cycle performance can be expected. On the other hand, it is preferable to set the amount of conductive agent and binder to 30% by mass or less each in order to achieve high capacity.

[0093] When the surface of the active material is coated with carbon or a conductive material, the amount of coating material can be considered as being included in the amount of conductive agent. The amount of carbon or conductive material coating is preferably 0.5% by mass or more and 5% by mass or less. Within this range of coating amounts, current collection performance and electrode density can be improved.

[0094] The current collector is made of a material that is electrochemically stable at the potential at which lithium (Li) is inserted into and removed from the active material. For example, when the active material is used as the negative electrode active material, the current collector is preferably made of copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. The thickness of the current collector is preferably 5 μm to 20 μm. A current collector with such a thickness can balance electrode strength and weight reduction.

[0095] Furthermore, the current collector may include portions on its surface where the active material-containing layer is not formed. These portions can function as current-collecting tabs.

[0096] Electrodes can be manufactured, for example, by the following method. First, an active material, a conductive agent, and a binder are suspended in a solvent to prepare a slurry. This slurry is applied to one or both sides of a current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. After that, this laminate is pressed. In this way, electrodes are manufactured.

[0097] Alternatively, electrodes may be manufactured by the following method: First, an active material, a conductive agent, and a binder are mixed to obtain a mixture. Next, this mixture is formed into pellets. Then, electrodes can be obtained by placing these pellets on a current collector.

[0098] The electrode according to the second embodiment contains the active material according to the first embodiment. Therefore, the electrode according to the second embodiment can realize a secondary battery with excellent rapid charge / discharge performance and cycle life performance.

[0099] (Third embodiment) According to the third embodiment, a secondary battery is provided that includes a negative electrode, a positive electrode, and an electrolyte. This secondary battery includes an electrode according to the second embodiment as either the negative electrode or the positive electrode. That is, the secondary battery according to the third embodiment includes an electrode containing the active material according to the first embodiment as the active material for the battery as the electrode for the battery. A preferred embodiment of the secondary battery includes an electrode according to the second embodiment as the negative electrode. That is, a preferred embodiment of the secondary battery includes an electrode containing the active material according to the first embodiment as the active material for the battery as the negative electrode. Preferred embodiments will be described below.

[0100] The secondary battery may further include a separator positioned between the positive electrode and the negative electrode. The negative electrode, positive electrode, and separator can constitute an electrode group. The electrolyte can be held within the electrode group.

[0101] Furthermore, the secondary battery may further comprise an outer casing that houses the electrode group and the electrolyte.

[0102] Furthermore, the secondary battery may further include a negative terminal electrically connected to the negative electrode and a positive terminal electrically connected to the positive electrode.

[0103] The secondary battery according to the third embodiment may be, for example, a lithium secondary battery. The secondary battery also includes a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte.

[0104] The following provides a detailed explanation of the negative electrode, positive electrode, electrolyte, separator, outer casing, negative electrode terminal, and positive electrode terminal.

[0105] 1) Negative electrode The negative electrode may include a negative electrode current collector and a negative electrode active material-containing layer. The negative electrode current collector and the negative electrode active material-containing layer may be a current collector and an active material-containing layer that can be included in the electrode according to the second embodiment, respectively. The negative electrode active material-containing layer contains the active material according to the first embodiment as the negative electrode active material.

[0106] Details of the negative electrode that overlap with the details described in the second embodiment will be omitted.

[0107] The density of the negative electrode active material layer (excluding the current collector) is 1.8 g / cm³. 3 More than 2.8g / cm 3 The following is preferable. A negative electrode with a density of the negative electrode active material-containing layer within this range exhibits excellent energy density and electrolyte retention. The density of the negative electrode active material-containing layer is 2.1 g / cm³. 3 More than 2.6g / cm 3 The following is more preferable:

[0108] The negative electrode can be manufactured, for example, by the same method as the electrode according to the second embodiment.

[0109] 2) Positive electrode The positive electrode may include a positive electrode current collector and a positive electrode active material-containing layer. The positive electrode active material-containing layer may be formed on one or both sides of the positive electrode current collector. The positive electrode active material-containing layer may optionally include a positive electrode active material and a conductive agent and a binder.

[0110] As the positive electrode active material, for example, an oxide or a sulfide can be used. The positive electrode may contain, as the positive electrode active material, one type of compound alone, or may contain a combination of two or more types of compounds. Examples of the oxide and the sulfide include compounds into which Li or Li ions can be inserted and desorbed.

[0111] Examples of such compounds include, for example, manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (for example, Li x Mn2O4 or Li x MnO2; 0 < x ≦ 1), lithium nickel composite oxide (for example, Li x NiO2; 0 < x ≦ 1), lithium cobalt composite oxide (for example, Li x CoO2; 0 < x ≦ 1), lithium nickel cobalt composite oxide (for example, Li x Ni 1-y Co y O2; 0 < x ≦ 1, 0 < y <1), lithium manganese cobalt composite oxide (for example, Li x Mn y Co 1-y O2; 0 < x ≦ 1, 0 < y <1), lithium manganese nickel composite oxide having a spinel structure (for example, Li x Mn 2-y Ni y O4; 0 < x ≦ 1, 0 < y < 2), lithium phosphate having an olivine structure (for example, Li x FePO4; 0 < x ≦ 1, Li x Fe 1-y Mn y PO4; 0 < x ≦ 1, 0 < y ≦ 1, Li x CoPO4; 0 < x ≦ 1), iron sulfate (Fe2(SO4)3), vanadium oxide (for example, V2O5), and lithium nickel cobalt manganese composite oxide (Li x Ni 1-y-z Co y Mn z O2; 0 < x ≦ 1, 0 < y < 1, y 0 < z < 1, y + z < 1) are included.

[0112] Among the above, examples of more preferable compounds as the positive electrode active material include lithium manganese composite oxides having a spinel structure (for example, Li x Mn2O4; 0 < x ≦ 1), lithium nickel composite oxides (for example, Li x NiO2; 0 < x ≦ 1), lithium cobalt composite oxides (for example, Li x CoO2; 0 < x ≦ 1), lithium nickel cobalt composite oxides (for example, Li x Ni 1-y Co y O2; 0 < x ≦ 1, 0 < y < 1), lithium manganese nickel composite oxides having a spinel structure (for example, Li x Mn 2-y Ni y O4; 0 < x ≦ 1, 0 < y < 2), lithium manganese cobalt composite oxides (for example, Li x Mn y Co 1-y O2; 0 < x ≦ 1, 0 < y < 1), lithium iron phosphate (for example, Li x FePO4; 0 < x ≦ 1), and lithium nickel cobalt manganese composite oxides (Li x Ni 1-y-z Co y Mn z O2; 0 < x ≦ 1, 0 < y < 1, 0 < z < 1, y + z < 1) are included. When these compounds are used as the positive electrode active material, the positive electrode potential can be increased.

[0113] When a room temperature molten salt is used as the electrolyte of the battery, it is preferable to use a positive electrode active material containing lithium iron phosphate, Li x ⏎ VPO4F (0 ≦ x ≦ 1), a lithium manganese composite oxide, a lithium nickel composite oxide, a lithium nickel cobalt composite oxide, or a mixture thereof. Since these compounds have low reactivity with the room temperature molten salt, the cycle life can be improved. Details of the room temperature molten salt will be described later.

[0114] The primary particle size of the positive electrode active material is preferably between 100 nm and 1 μm. Positive electrode active material with a primary particle size of 100 nm or more is easy to handle in industrial production. Positive electrode active material with a primary particle size of 1 μm or less allows for smooth diffusion of lithium ions within the solid.

[0115] The specific surface area of ​​the positive electrode active material is 0.1 m². 2 / g or more 10m 2 It is preferable that it is less than or equal to / g. 0.1m 2 A positive electrode active material having a specific surface area of ​​10m or more can adequately secure Li ion insertion and deinsertion sites. 2 Positive electrode active materials with a specific surface area of ​​less than / g are easy to handle in industrial production and can ensure good charge-discharge cycle performance.

[0116] A binder is added to fill the gaps between dispersed positive electrode active materials and to bond the positive electrode active materials to the positive electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as a binder, or two or more may be used in combination.

[0117] Conductive agents are added to enhance current collection performance and reduce contact resistance between the positive electrode active material and the positive electrode current collector. Examples of conductive agents include vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, and carbonaceous materials such as graphite. One of these may be used as a conductive agent, or two or more may be used in combination. Conductive agents may also be omitted.

[0118] In the positive electrode active material-containing layer, it is preferable that the positive electrode active material and the binder are blended in proportions of 80% to 98% by mass and 2% to 20% by mass, respectively.

[0119] Sufficient electrode strength can be obtained by using a binder amount of 2% by mass or more. Furthermore, the binder can function as an insulator. Therefore, reducing the binder amount to 20% by mass or less reduces the amount of insulator contained in the electrode, thereby reducing internal resistance.

[0120] When a conductive agent is added, it is preferable that the positive electrode active material, binder, and conductive agent are blended in proportions of 77% to 95% by mass, 2% to 20% by mass, and 3% to 15% by mass, respectively.

[0121] The above-mentioned effects can be achieved by increasing the amount of conductive agent to 3% by mass or more. Furthermore, by reducing the amount of conductive agent to 15% by mass or less, the proportion of conductive agent in contact with the electrolyte can be reduced. This lower proportion reduces the decomposition of the electrolyte under high-temperature storage conditions.

[0122] The positive electrode current collector is preferably an aluminum foil, or an aluminum alloy foil containing one or more elements selected from the group consisting of Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si.

[0123] The thickness of the aluminum foil or aluminum alloy foil is preferably 5 μm or more and 20 μm or less, and more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. The content of transition metals such as iron, copper, nickel, and chromium in the aluminum foil or aluminum alloy foil is preferably 1% by mass or less.

[0124] Furthermore, the positive electrode current collector may include portions on its surface where the positive electrode active material-containing layer is not formed. These portions can function as positive electrode current collector tabs.

[0125] The positive electrode can be manufactured, for example, using a positive electrode active material in the same manner as the electrode according to the second embodiment.

[0126] 3) Electrolytes As the electrolyte, for example, a liquid non-aqueous electrolyte or a gel-type non-aqueous electrolyte can be used. A liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt as a solute in an organic solvent. The concentration of the electrolyte salt is preferably 0.5 mol / L or more and 2.5 mol / L or less.

[0127] Examples of electrolyte salts include lithium perchlorate (LiClO4), lithium hexafluoride phosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium arsenide hexafluoride (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium salts such as bistrifluoromethylsulfonylimide lithium (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(SO2F)2; LiFSI), and mixtures thereof. The electrolyte salt is preferably resistant to oxidation even at high potentials, with LiPF6 being the most preferred.

[0128] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); linear carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); cyclic ethers such as tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2MeTHF), and dioxolane (DOX); linear ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); and γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane (SL). These organic solvents can be used alone or as mixed solvents.

[0129] Gel-like non-aqueous electrolytes are prepared by compounding a liquid non-aqueous electrolyte with a polymer material. Examples of polymer materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

[0130] Alternatively, in addition to liquid nonaqueous electrolytes and gel-type nonaqueous electrolytes, room-temperature molten salts (ionic melts) containing lithium ions, polymer solid electrolytes, and inorganic solid electrolytes may be used as nonaqueous electrolytes.

[0131] Room temperature molten salts (ionic melts) refer to organic salts consisting of a combination of organic cations and anions that can exist as liquids at room temperature (15°C to 25°C). Room temperature molten salts include room temperature molten salts that exist as liquids on their own, room temperature molten salts that become liquid when mixed with an electrolyte salt, room temperature molten salts that become liquid when dissolved in an organic solvent, or mixtures thereof. Generally, the melting point of room temperature molten salts used in secondary batteries is 25°C or lower. Also, organic cations generally have a quaternary ammonium skeleton.

[0132] Polymeric solid electrolytes are prepared by dissolving an electrolyte salt in a polymer material and then solidifying it.

[0133] Inorganic solid electrolytes are solid materials that have lithium ion conductivity. Here, "having lithium ion conductivity" means that at 25°C, they have a conductivity of 1 × 10⁻⁶. -6 This refers to exhibiting a lithium ion conductivity of S / cm or higher. Examples of inorganic solid electrolytes include oxide-based solid electrolytes and sulfide-based solid electrolytes. Specific examples of inorganic solid electrolytes are as follows.

[0134] As an oxide-based solid electrolyte, it has a NASICON (Sodium (Na) Super Ionic Conductor) type structure, and its general formula is Li 1+x It is preferable to use a lithium phosphate solid electrolyte represented by Mα2(PO4)3. In the above general formula, Mα is one or more selected from the group consisting of, for example, titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is in the range of 0 ≤ x ≤ 2.

[0135] A specific example of a lithium phosphate solid electrolyte having a NASICON-type structure is Li 1+x Al x Ti 2-x LATP compounds represented as (PO4)3 where 0.1 ≤ x ≤ 0.5; Li 1+x Al y Mβ 2-yA compound represented by (PO4)3, where Mβ is one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1; Li 1+x Al x Ge 2-x A compound represented by (PO4)3, where 0 ≦ x ≦ 2; and, Li 1+x Al x Zr 2-x A compound represented by (PO4)3, where 0 ≦ x ≦ 2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 A compound represented by, where Mγ is one or more selected from the group consisting of Ti and Ge, 0 < x ≦ 2, and 0 ≦ y < 3; Li 1+2x Zr 1-x Ca x Examples of compounds represented by (PO4)3, where 0 ≦ x < 1, can be given.

[0136] In addition, as the oxide-based solid electrolyte, in addition to the above lithium phosphate solid electrolyte, Li x PO y N z An amorphous LIPON compound represented by, where 2.6 ≦ x ≦ 3.5, 1.9 ≦ y ≦ 3.8, and 0.1 ≦ z ≦ 1.3 (for example, Li 2.9 PO 3.3 N 0.46 ); A garnet-type structure La 5+ xA<00002​​​​​​​​​​​​​​​​​​​​​12 Represented by , where Mδ is 1 or more selected from the group consisting of Nb and Ta, and 0 ≤ x ≤ 2, it is an LLZ compound (e.g., Li7La3Zr2O 12 ); and having a perovskite-type structure La 2 / 3-x Li x Examples include compounds represented as TiO3 where 0.3 ≤ x ≤ 0.7.

[0137] One or more of the above compounds can be used as a solid electrolyte. Two or more of the above solid electrolytes may also be used.

[0138] Alternatively, a liquid aqueous electrolyte or a gel-type aqueous electrolyte can be used as the electrolyte instead of a non-aqueous electrolyte. A liquid aqueous electrolyte is prepared by dissolving, for example, the electrolyte salt in an aqueous solvent as the solute. A gel-type aqueous electrolyte is prepared by compounding a liquid aqueous electrolyte with the polymer material. As the aqueous solvent, a solution containing water may be used. The solution containing water may be pure water or a mixed solvent of water and an organic solvent.

[0139] 4) Separator The separator is formed from a porous film containing, for example, polyethylene (PE), polypropylene (PP), cellulose, or polyvinylidene fluoride (PVdF), or from a synthetic resin nonwoven fabric. From a safety standpoint, it is preferable to use a porous film made of polyethylene or polypropylene. This is because these porous films can melt at a certain temperature and interrupt the electric current.

[0140] 5) Exterior components For example, the outer packaging material can be a container made of laminate film or a metal container.

[0141] The thickness of the laminating film is, for example, 0.5 mm or less, and preferably 0.2 mm or less.

[0142] As the laminate film, a multilayer film is used that includes multiple resin layers and a metal layer interposed between these resin layers. The resin layers include polymer materials such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). The metal layer is preferably made of aluminum foil or aluminum alloy foil for weight reduction. The laminate film can be molded into the shape of an exterior component by sealing it by heat fusion.

[0143] The thickness of the metal container wall is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0144] Metal containers are made from, for example, aluminum or aluminum alloys. Aluminum alloys preferably contain elements such as magnesium, zinc, and silicon. If aluminum alloys contain transition metals such as iron, copper, nickel, and chromium, their content is preferably 1% by mass or less.

[0145] The shape of the exterior components is not particularly limited. For example, the exterior components may be flat (thin), rectangular, cylindrical, coin-shaped, or button-shaped. The exterior components can be appropriately selected according to the battery dimensions and intended use.

[0146] 6) Negative terminal The negative electrode terminal can be formed from a material that is electrochemically stable at the Li insertion / deinsertion potential of the negative electrode active material described above, and that is also conductive. Specifically, the material for the negative electrode terminal can be copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. It is preferable to use aluminum or an aluminum alloy as the material for the negative electrode terminal. It is preferable that the negative electrode terminal be made of the same material as the negative electrode current collector in order to reduce contact resistance with the negative electrode current collector.

[0147] 7) Positive terminal The positive terminal has a potential range of 3V to 4.5V relative to the oxidation-reduction potential of lithium (vs.Li / Li + The positive electrode terminal can be formed from an electrically stable and conductive material. Examples of positive electrode terminal materials include aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. It is preferable that the positive electrode terminal be formed from the same material as the positive electrode current collector in order to reduce contact resistance with the positive electrode current collector.

[0148] The above describes an embodiment of the secondary battery in which the electrode according to the second embodiment is used as the negative electrode. In the embodiment of the secondary battery according to the third embodiment in which the electrode according to the second embodiment is used as the positive electrode, for example, the following types of counter electrodes can be used as the negative electrode. At least one electrode selected from lithium metal, lithium metal alloy, graphite, silicon, silicon oxide, tin oxide, silicon, tin, and other alloys can be used as the negative electrode. Materials that do not contain Li in the active material can be used as the negative electrode by pre-doping with the element Li.

[0149] In an embodiment that includes the electrode according to the second embodiment as the positive electrode, the details of the positive electrode are omitted because they overlap with those described in the second embodiment.

[0150] Next, a secondary battery according to the third embodiment will be described in more detail with reference to the drawings.

[0151] Figure 3 is a schematic cross-sectional view showing an example of a secondary battery. Figure 4 is an enlarged cross-sectional view of part A of the secondary battery shown in Figure 3.

[0152] The secondary battery 100 shown in Figures 3 and 4 comprises an electrode group 1 shown in Figure 3, a bag-shaped outer casing member 2 shown in Figures 3 and 4, and an electrolyte (not shown). The electrode group 1 and the electrolyte are housed within the bag-shaped outer casing member 2. The electrolyte (not shown) is held by the electrode group 1.

[0153] The bag-shaped outer packaging member 2 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0154] As shown in Figure 3, electrode group 1 is a flat, wound electrode group. As shown in Figure 4, the flat, wound electrode group 1 includes a negative electrode 3, a separator 4, and a positive electrode 5. The separator 4 is interposed between the negative electrode 3 and the positive electrode 5.

[0155] The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode active material containing layer 3b. In the portion of the negative electrode 3 located in the outermost shell of the wound electrode group 1, the negative electrode active material containing layer 3b is formed only on the inner surface side of the negative electrode current collector 3a, as shown in Figure 4. In the other portions of the negative electrode 3, the negative electrode active material containing layer 3b is formed on both sides of the negative electrode current collector 3a.

[0156] The positive electrode 5 includes a positive electrode current collector 5a and positive electrode active material-containing layers 5b formed on both sides thereof.

[0157] As shown in Figure 3, the negative electrode terminal 6 and the positive electrode terminal 7 are located near the outer edge of the wound electrode group 1. The negative electrode terminal 6 is connected to the outermost part of the negative electrode current collector 3a. The positive electrode terminal 7 is connected to the outermost part of the positive electrode current collector 5a. These negative electrode terminals 6 and positive electrode terminals 7 extend outward from the opening of the bag-shaped outer casing member 2. A thermoplastic resin layer is installed on the inner surface of the bag-shaped outer casing member 2, and the opening is closed by heat-sealing this layer.

[0158] The secondary battery according to this embodiment is not limited to the secondary battery with the configuration shown in Figures 3 and 4, but may also be a battery with the configuration shown in Figures 5 and 6, for example.

[0159] Figure 5 is a schematic partially cutaway perspective view showing another example of a secondary battery. Figure 6 is an enlarged cross-sectional view of section B of the secondary battery shown in Figure 5.

[0160] The secondary battery 100 shown in Figures 5 and 6 comprises an electrode group 1 shown in Figures 5 and 6, an outer casing member 2 shown in Figure 5, and an electrolyte (not shown). The electrode group 1 and the electrolyte are housed within the outer casing member 2. The electrolyte is held within the electrode group 1.

[0161] The exterior component 2 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0162] As shown in Figure 6, electrode group 1 is a stacked electrode group. The stacked electrode group 1 has a structure in which negative electrodes 3 and positive electrodes 5 are stacked alternately with a separator 4 interposed between them.

[0163] The electrode group 1 includes a plurality of negative electrodes 3. Each of the plurality of negative electrodes 3 comprises a negative electrode current collector 3a and a negative electrode active material-containing layer 3b supported on both sides of the negative electrode current collector 3a. The electrode group 1 also includes a plurality of positive electrodes 5. Each of the plurality of positive electrodes 5 comprises a positive electrode current collector 5a and a positive electrode active material-containing layer 5b supported on both sides of the positive electrode current collector 5a.

[0164] Each negative electrode 3's negative electrode current collector 3a includes a portion on one side where the negative electrode active material-containing layer 3b is not supported on any surface. This portion functions as a negative electrode current collector tab 3c. As shown in Figure 6, the negative electrode current collector tab 3c does not overlap with the positive electrode 5. Furthermore, multiple negative electrode current collector tabs 3c are electrically connected to a strip-shaped negative electrode terminal 6. The tip of the strip-shaped negative electrode terminal 6 is extended to the outside of the outer casing member 2.

[0165] Although not shown in the diagram, the positive electrode current collector 5a of each positive electrode 5 includes a portion on one side where the positive electrode active material-containing layer 5b is not supported on any surface. This portion functions as a positive electrode current collector tab. The positive electrode current collector tab, like the negative electrode current collector tab 3c, does not overlap with the negative electrode 3. Furthermore, the positive electrode current collector tab is located on the opposite side of the electrode group 1 from the negative electrode current collector tab 3c. The positive electrode current collector tab is electrically connected to a strip-shaped positive electrode terminal 7. The tip of the strip-shaped positive electrode terminal 7 is located on the opposite side from the negative electrode terminal 6 and is extended to the outside of the outer casing member 2.

[0166] The secondary battery according to the third embodiment includes the electrode according to the second embodiment. In other words, the secondary battery according to the third embodiment includes the electrode containing the active material according to the first embodiment. Therefore, the secondary battery according to the third embodiment has excellent rapid charge / discharge performance and cycle life performance.

[0167] (Fourth embodiment) According to the fourth embodiment, a battery pack is provided. This battery pack comprises a plurality of secondary batteries according to the third embodiment.

[0168] In such a battery pack, each individual cell may be arranged in series or parallel connections, or a combination of series and parallel connections may be used.

[0169] Next, an example of a battery pack according to the fourth embodiment will be described with reference to the drawings.

[0170] FIG. 7 is a perspective view schematically showing an example of an assembled battery. The assembled battery 200 shown in FIG. 7 includes five single batteries 100a to 100e, four bus bars 21, a positive electrode side lead 22, and a negative electrode side lead 23. Each of the five single batteries 100a to 100e is a secondary battery according to the third embodiment.

[0171] The bus bar 21 connects, for example, the negative electrode terminal 6 of one single battery 100a and the positive electrode terminal 7 of the adjacent single battery 100b. In this way, the five single batteries 100 are connected in series by the four bus bars 21. That is, the assembled battery 200 in FIG. 7 is a five-series assembled battery. Although not illustrated, in an assembled battery including a plurality of single batteries that are electrically connected in parallel, for example, a plurality of negative electrode terminals are connected by a bus bar and a plurality of positive electrode terminals are connected by a bus bar, so that the plurality of single batteries can be electrically connected.

[0172] The positive electrode terminal 7 of at least one battery among the five single batteries 100a to 100e is electrically connected to the positive electrode side lead 22 for external connection. Also, the negative electrode terminal 6 of at least one battery among the five single batteries 100a to 100e is electrically connected to the negative electrode side lead 23 for external connection.

[0173] The assembled battery according to the fourth embodiment includes the secondary battery according to the third embodiment. Therefore, such an assembled battery is excellent in rapid charge and discharge performance and cycle life performance.

[0174] (Fifth Embodiment) According to the fifth embodiment, a battery pack is provided. This battery pack includes the assembled battery according to the fourth embodiment. This battery pack may include a single secondary battery according to the third embodiment instead of the assembled battery according to the fourth embodiment.

[0175] The battery pack may further include a protection circuit. The protection circuit has a function of controlling charging and discharging of the secondary battery. Alternatively, a circuit included in a device (e.g., an electronic device, an automobile, etc.) that uses the battery pack as a power source may be used as the protection circuit of the battery pack.

[0176] Also, the battery pack may further include external terminals for energization. The external terminals for energization are for outputting a current from the secondary battery to the outside and / or inputting an external current to the secondary battery. In other words, when the battery pack is used as a power source, the current is supplied to the outside through the external terminals for energization. Also, when the battery pack is charged, the charging current (including regenerative energy of power such as in an automobile) is supplied to the battery pack through the external terminals for energization.

[0177] Next, an example of the battery pack according to the embodiment will be described while referring to the drawings.

[0178] FIG. 8 is an exploded perspective view schematically showing an example of the battery pack. FIG. 9 is a block diagram showing an example of the electrical circuit of the battery pack shown in FIG. 8.

[0179] The battery pack 300 shown in FIGS. 8 and 9 includes a housing container 31, a lid 32, a protective sheet 33, a battery module 200, a printed wiring board 34, wiring 35, and an insulating board (not shown).

[0180] The housing container 31 shown in FIG. 8 is a bottomed rectangular container having a rectangular bottom surface. The housing container 31 is configured to be able to accommodate the protective sheet 33, the battery module 200, the printed wiring board 34, and the wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the housing container 31 to accommodate the battery module 200 and the like. Although not shown, the housing container 31 and the lid 32 are provided with openings or connection terminals for connecting to external devices or the like.

[0181] The battery module 200 includes a plurality of single cells 100, a positive electrode side lead 22, a negative electrode side lead 23, and an adhesive tape 24.

[0182] At least one of the multiple single cells 100 is a secondary battery according to the third embodiment. Each of the multiple single cells 100 is electrically connected in series as shown in Figure 9. The multiple single cells 100 may also be electrically connected in parallel, or they may be connected in a combination of series and parallel connections. When the multiple single cells 100 are connected in parallel, the battery capacity increases compared to when they are connected in series.

[0183] The adhesive tape 24 fastens multiple single cells 100 together. Alternatively, heat-shrinkable tape may be used to secure the multiple single cells 100 instead of the adhesive tape 24. In this case, protective sheets 33 are placed on both sides of the battery pack 200, the heat-shrinkable tape is wrapped around it, and then the heat-shrinkable tape is heat-shrinked to bundle the multiple single cells 100 together.

[0184] One end of the positive lead 22 is connected to the battery pack 200. One end of the positive lead 22 is electrically connected to the positive terminal of one or more single cells 100. One end of the negative lead 23 is connected to the battery pack 200. One end of the negative lead 23 is electrically connected to the negative terminal of one or more single cells 100.

[0185] The printed circuit board 34 is installed along one of the shorter sides of the inner surface of the housing container 31. The printed circuit board 34 includes a positive terminal connector 342, a negative terminal connector 343, a thermistor 345, a protection circuit 346, wiring 342a and 343a, an external terminal 350 for energization, a positive side wiring (positive wiring) 348a, and a negative side wiring (negative wiring) 348b. One main surface of the printed circuit board 34 faces one side of the battery pack 200. An insulating plate (not shown) is interposed between the printed circuit board 34 and the battery pack 200.

[0186] The other end 22a of the positive lead 22 is electrically connected to the positive connector 342. The other end 23a of the negative lead 23 is electrically connected to the negative connector 343.

[0187] The thermistor 345 is fixed to one main surface of the printed circuit board 34. The thermistor 345 detects the temperature of each of the single cells 100 and transmits the detection signal to the protection circuit 346.

[0188] The external power supply terminal 350 is fixed to the other main surface of the printed circuit board 34. The external power supply terminal 350 is electrically connected to equipment located outside the battery pack 300. The external power supply terminal 350 includes a positive terminal 352 and a negative terminal 353.

[0189] The protection circuit 346 is fixed to the other main surface of the printed circuit board 34. The protection circuit 346 is connected to the positive terminal 352 via the positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via the negative side wiring 348b. The protection circuit 346 is also electrically connected to the positive side connector 342 via wiring 342a. The protection circuit 346 is also electrically connected to the negative side connector 343 via wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the multiple single cells 100 via wiring 35.

[0190] The protective sheet 33 is positioned on both inner surfaces in the long-side direction of the housing container 31 and on the inner surface in the short-side direction facing the printed circuit board 34 via the battery pack 200. The protective sheet 33 is made of, for example, resin or rubber.

[0191] The protection circuit 346 controls the charging and discharging of multiple single cells 100. The protection circuit 346 also disconnects the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) for supplying power to external devices, based on a detection signal transmitted from the thermistor 345 or a detection signal transmitted from an individual single cell 100 or a battery pack 200.

[0192] An example of a detection signal transmitted from the thermistor 345 is a signal indicating that the temperature of a single cell 100 is above a predetermined temperature. An example of a detection signal transmitted from an individual single cell 100 or a battery pack 200 is a signal indicating that overcharging, over-discharging, or overcurrent has been detected in a single cell 100. When detecting overcharging, etc., in an individual single cell 100, the battery voltage may be detected, or the positive electrode potential or negative electrode potential may be detected. In the latter case, a lithium electrode to be used as a reference electrode is inserted into each individual single cell 100.

[0193] Furthermore, the protection circuit 346 may be a circuit included in a device that uses the battery pack 300 as a power source (for example, an electronic device, an automobile, etc.).

[0194] Furthermore, as described above, the battery pack 300 is equipped with an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device and input current from an external device to the battery pack 200 via the external terminal 350. In other words, when the battery pack 300 is used as a power source, current from the battery pack 200 is supplied to the external device through the external terminal 350. Also, when charging the battery pack 300, charging current from an external device is supplied to the battery pack 300 through the external terminal 350. When this battery pack 300 is used as an on-board battery, the regenerative energy of the vehicle's power can be used as the charging current from the external device.

[0195] The battery pack 300 may have multiple battery packs 200. In this case, the multiple battery packs 200 may be connected in series, in parallel, or in a combination of series and parallel connections. The printed circuit board 34 and wiring 35 may also be omitted. In this case, the positive lead 22 and the negative lead 23 may be used as the positive terminal 352 and negative terminal 353 of the external terminal 350 for energization, respectively.

[0196] Such a battery pack is used in applications where excellent cycle performance is required, for example, when drawing a large current. Specifically, this battery pack is used, for example, as a power source for electronic devices, a stationary battery, or an in-vehicle battery for various vehicles. Examples of electronic devices include, for example, digital cameras. This battery pack is particularly preferably used as an in-vehicle battery.

[0197] The battery pack according to the fifth embodiment includes the secondary battery according to the third embodiment or the assembled battery according to the fourth embodiment. Therefore, such a battery pack is excellent in rapid charge / discharge performance and cycle life performance.

[0198] (Sixth Embodiment) According to the sixth embodiment, a vehicle is provided. This vehicle is equipped with the battery pack according to the fifth embodiment.

[0199] In such a vehicle, the battery pack, for example, recovers the regenerative energy of the vehicle's power. The vehicle may include a mechanism (Regenerator) that converts the vehicle's kinetic energy into regenerative energy.

[0200] Examples of vehicles include, for example, two- to four-wheel hybrid electric vehicles, two- to four-wheel electric vehicles, assist bicycles, and railway vehicles.

[0201] The mounting position of the battery pack in the vehicle is not particularly limited. For example, when mounting the battery pack in an automobile, the battery pack can be mounted in the vehicle's engine room, behind the vehicle body, or under the seat.

[0202] A vehicle may be equipped with multiple battery packs. In this case, the batteries contained in each battery pack may be electrically connected in series, in parallel, or a combination of series and parallel connections. For example, if each battery pack contains a battery pack, the battery packs may be electrically connected in series, in parallel, or a combination of series and parallel connections. Alternatively, if each battery pack contains a single battery, the batteries may be electrically connected in series, in parallel, or a combination of series and parallel connections.

[0203] Next, an example of a vehicle according to the embodiment will be described with reference to the drawings.

[0204] Figure 10 is a schematic partial transparency drawing showing an example of a vehicle.

[0205] The vehicle 400 shown in Figure 10 includes a vehicle body 40 and a battery pack 300 according to the fifth embodiment. In the example shown in Figure 10, the vehicle 400 is a four-wheeled automobile.

[0206] This vehicle 400 may be equipped with multiple battery packs 300. In this case, the batteries contained in the battery pack 300 (for example, single cells or battery packs) may be connected in series, in parallel, or in a combination of series and parallel connections.

[0207] Figure 10 illustrates an example in which the battery pack 300 is mounted in the engine compartment located in front of the vehicle body 40. As described above, the battery pack 300 may also be mounted, for example, in the rear of the vehicle body 40 or under the seats. This battery pack 300 can be used as a power source for the vehicle 400. In addition, this battery pack 300 can recover regenerative energy from the vehicle 400's power.

[0208] Next, an embodiment of the vehicle according to the embodiment will be described with reference to Figure 11.

[0209] Figure 11 is a schematic diagram illustrating an example of a control system for the electrical system in a vehicle. The vehicle 400 shown in Figure 11 is an electric vehicle.

[0210] The vehicle 400 shown in Figure 11 comprises a vehicle body 40, a vehicle power supply 41, a vehicle ECU (ECU: Electric Control Unit) 42 which is a control device higher up than the vehicle power supply 41, an external terminal (terminal for connecting to an external power supply) 43, an inverter 44, and a drive motor 45.

[0211] Vehicle 400 has a vehicle power supply 41 mounted, for example, in the engine compartment, at the rear of the vehicle body, or under the seats. Note that in the vehicle 400 shown in Figure 11, the mounting location of the vehicle power supply 41 is shown in a schematic manner.

[0212] The vehicle power supply 41 comprises a plurality (for example, three) of battery packs 300a, 300b, and 300c, a battery management unit (BMU) 411, and a communication bus 412.

[0213] Battery pack 300a comprises a battery pack 200a and a battery pack monitoring device 301a (e.g., VTM: Voltage Temperature Monitoring). Battery pack 300b comprises a battery pack 200b and a battery pack monitoring device 301b. Battery pack 300c comprises a battery pack 200c and a battery pack monitoring device 301c. Battery packs 300a to 300c are similar to the aforementioned battery pack 300, and battery packs 200a to 200c are similar to the aforementioned battery pack 200. Battery packs 200a to 200c are electrically connected in series. Battery packs 300a, 300b, and 300c can each be independently removed and replaced with another battery pack 300.

[0214] Each of the battery packs 200a to 200c comprises multiple single cells connected in series. At least one of the multiple single cells is a secondary battery according to the third embodiment. Each of the battery packs 200a to 200c is charged and discharged through a positive terminal 413 and a negative terminal 414.

[0215] The battery management device 411 communicates with the battery pack monitoring devices 301a to 301c and collects information such as voltage and temperature for each of the single cells 100 included in the battery packs 200a to 200c included in the vehicle power supply 41. In this way, the battery management device 411 collects information related to the maintenance of the vehicle power supply 41.

[0216] The battery management device 411 and the battery pack monitoring devices 301a to 301c are connected via a communication bus 412. On the communication bus 412, one set of communication lines is shared by multiple nodes (the battery management device 411 and one or more battery pack monitoring devices 301a to 301c). The communication bus 412 is a communication bus configured, for example, based on the CAN (Control Area Network) standard.

[0217] The battery pack monitoring devices 301a to 301c measure the voltage and temperature of each individual cell constituting the battery packs 200a to 200c based on commands communicated from the battery management device 411. However, temperature can be measured at only a few locations per battery pack, and it is not necessary to measure the temperature of all individual cells.

[0218] The vehicle power supply 41 may also have an electromagnetic contactor (for example, a switch device 415 shown in Figure 11) that switches the presence or absence of an electrical connection between the positive terminal 413 and the negative terminal 414. The switch device 415 includes a pre-charge switch (not shown) that turns on when charging is performed on the battery packs 200a to 200c, and a main switch (not shown) that turns on when the output from the battery packs 200a to 200c is supplied to the load. Each of the pre-charge switch and the main switch includes a relay circuit (not shown) that is switched on or off by a signal supplied to a coil located near the switch element. Electromagnetic contactors such as the switch device 415 are controlled based on a control signal from the battery management device 411 or the vehicle ECU 42 that controls the operation of the entire vehicle 400.

[0219] The inverter 44 converts the input DC voltage into a high voltage of three-phase alternating current (AC) for motor drive. The three-phase output terminals of the inverter 44 are connected to the three-phase input terminals of the drive motor 45. The inverter 44 is controlled based on control signals from the battery management device 411 or the vehicle ECU 42 for controlling the operation of the entire vehicle. By controlling the inverter 44, the output voltage from the inverter 44 is adjusted.

[0220] The drive motor 45 rotates using power supplied from the inverter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and drive wheels W, for example, via a differential gear unit.

[0221] Although not shown in the diagram, vehicle 400 is also equipped with a regenerative braking mechanism (regenerator). The regenerative braking mechanism rotates the drive motor 45 when vehicle 400 is braked, converting kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to the inverter 44 and converted into a DC current. The converted DC current is input to the vehicle power supply 41.

[0222] One terminal of connection line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of connection line L1 is connected to the negative input terminal 417 of the inverter 44. A current detection unit (current detection circuit) 416 within the battery management device 411 is provided on connection line L1 between the negative terminal 414 and the negative input terminal 417.

[0223] One terminal of connection line L2 is connected to the positive terminal 413 of the vehicle power supply 41. The other terminal of connection line L2 is connected to the positive input terminal 418 of the inverter 44. A switch device 415 is provided between the positive terminal 413 and the positive input terminal 418 of connection line L2.

[0224] External terminal 43 is connected to battery management device 411. External terminal 43 can be connected to an external power supply, for example.

[0225] The vehicle ECU 42, in response to operational inputs from the driver and others, coordinates control of the vehicle power supply 41, switch device 415, inverter 44, etc., together with other management and control devices, including the battery management device 411. Through the coordinated control of the vehicle ECU 42, etc., the output of power from the vehicle power supply 41 and the charging of the vehicle power supply 41 are controlled, and the entire vehicle 400 is managed. Data related to the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transferred between the battery management device 411 and the vehicle ECU 42 via a communication line.

[0226] The vehicle according to the sixth embodiment is equipped with a battery pack according to the fifth embodiment. Because the battery pack has excellent rapid charge and discharge performance, the vehicle can exhibit high performance. In addition, because the battery pack has excellent cycle life performance, the vehicle is highly reliable. [Examples]

[0227] The embodiments described above will be further explained below based on the examples. However, the present invention is not limited to the examples listed below.

[0228] <Synthesis> (Example 1) The following titanium-niobium-molybdenum composite oxide was synthesized.

[0229] As raw materials, ammonium niobium oxalate, ammonium molybdate, and titanium tetraisopropoxide were prepared. These raw materials were weighed according to a predetermined composition ratio. Solution A was prepared by dissolving ammonium niobium oxalate and ammonium molybdate in pure water. Next, solution B was prepared by adding titanium tetraisopropoxide to a 1 M aqueous solution of oxalic acid and dissolving it by heating and stirring. After mixing solution A and solution B, a sol was obtained by adding ammonia solution while heating and stirring to adjust the pH to 7. The solvent was evaporated from the sol by spray drying at a drying temperature of 180°C to obtain a white precursor powder. The precursor powder was placed in an alumina crucible and calcined in air at 700°C for 4 hours. After that, the calcined material was dry-ground, and the particle size was adjusted by classifying the ground material. Active material powder was obtained in the manner described above.

[0230] (Example 2) The composite oxide was synthesized in the same manner as in Example 1, except that the temperature for calcining the precursor was changed to 800°C, and an active material powder was obtained.

[0231] (Example 3) The composite oxide was synthesized in the same manner as in Example 1, except that the calcination temperature of the precursor was changed to 900°C, and an active material powder was obtained.

[0232] (Examples 4-7) A composite oxide was synthesized in the same manner as in Example 1, except that the composition ratio of the precursor was changed by adjusting the weighing ratio of the raw materials, and the calcination temperature of the precursor was changed as follows, to obtain an active material powder. The calcination temperature was 700°C in Example 4, 750°C in Example 5, 800°C in Example 6, and 900°C in Example 7.

[0233] (Comparative Example 1) The composite oxide was synthesized in the same manner as in Example 1, except that the calcination temperature of the precursor powder was changed to 600°C, and an active material powder was obtained.

[0234] <Measurement> Scanning transmission electron microscopy was performed on the powders obtained in each of the above examples and comparative examples. Specifically, as detailed above, the fine structure was observed using a 10 nm × 10 nm image obtained with a STEM-HAADF imager equipped with spherical aberration correction. Wide-angle X-ray scattering measurements were also performed. The measurements were carried out according to the details described above. Crystal structure analysis was performed on the obtained spectra using the Rietveld method. In addition, ICP emission spectrometry, HAXPES measurements, and Raman spectroscopy measurements were performed. Some of the measurement results are described in detail below.

[0235] In the composite oxide obtained in Example 1, it was confirmed that the crystal structures shown in Figures 1 and 2 were present in combination.

[0236] The metal ratio of the composite oxide obtained in Example 1 was calculated by ICP analysis, and it was determined to be Ti:Nb:Mo = 0.23:1.00:0.18. The valence was evaluated by HAXPES measurement. The Ti element was within the range of 459±0.4eV (Ti2p). 3 / 2 A single peak originating from [source] was observed, leading to its identification as tetravalent. The Nb element was found within the range of 207.5±eV, specifically Nb5d 3 / 2 A single peak top originating from [source] was observed, leading to its identification as pentavalent. The element Mo originated from Mo3d at 232.2±0.3 eV, which is hexavalent. 5 / 2 A peak was observed, and it was confirmed that different peaks were present at a value 1 eV lower than that peak, thus identifying the presence of both pentavalent and hexavalent peaks. Based on the peak mixing ratio, it was estimated that pentavalent and hexavalent elements were present in a 7:3 ratio, and the average valency was assumed to be 5.3. The empirical formula calculated under this assumption is Ti 0.23 NbMo 0.18 O 3.47 Therefore, b=0.23, c=0.18, and d=3.47.

[0237] In Example 2, it was confirmed that the composite oxide contained both the crystal structures shown in Figure 1 and Figure 2.

[0238] The metal ratio of the composite oxide obtained in Example 2 was calculated by ICP analysis, and it was found to be Ti:Nb:Mo = 0.23:1.00:0.18. The valence was evaluated by HAXPES measurement using the same method as in Example 1, and it was determined that Ti was valence 4, Nb was valence 5, and Mo was valence 5.6. The compositional formula calculated from the valence is: Ti 0.23 NbMo 0.18 O 3.49 Therefore, b=0.23, c=0.18, and d=3.49.

[0239] The composite oxide obtained in Example 3 was identified as a single phase with only the crystal structure shown in Figure 1 based on structural analysis.

[0240] The metallicity of the composite oxide obtained in Example 3 was calculated by ICP analysis, and it was found to be Ti:Nb:Mo = 0.23:1.00:0.15. The compositional formula calculated from the number of elements and crystal structure is Ti 0.23 NbMo 0.15 O 3.45 The valency was evaluated by HAXPES measurement using the same method as in Example 1, and the Ti valency was found to be 4, the Nb valency to be 5, and the Mo valency to be 6. The compositional formula calculated from the valency is: Ti 0.23 NbMo 0.15 O 3.41 Therefore, b=0.23, c=0.15, and d=3.41.

[0241] Although details are omitted, in Examples 4 and 5, composite oxides were obtained in which the crystal structures shown in Figures 1 and 2 coexisted. In Examples 6 and 7, similar to Example 3, composite oxides with a single phase of the crystal structure shown in Figure 1 were obtained. General formula Li a M b NbMo c O d The composition represented by was as shown in Table 1 below.

[0242] For the composite oxide obtained in Comparative Example 1, microstructure observation using STEM-HAADF imaging revealed that the size of the ReO3 blocks within the field of view differed, and a crystal structure was confirmed in which octahedral edges were shared without periodicity. Therefore, it was identified as the crystal structure shown in Figure 2. In addition, in different fields of view, connection regions including tetrahedral vertex sharing were also observed.

[0243] For the composite oxide obtained in Comparative Example 1, the metal ratio was calculated by ICP analysis and found to be Ti:Nb:Mo = 0.23:1.00:0.23. The valence was evaluated by HAXPES measurement using the same method as in Example 1, and the Ti valence was found to be 4, the Nb valence to be 5, and the Mo valence to be 5.5. The compositional formula calculated from the valence is: Ti 0.23 NbMo0. 23 O 3.59 Therefore, b=0.23, c=0.23, and d=3.59.

[0244] Figure 12 shows the spectra obtained by micro-Raman spectroscopy (excitation wavelength: 532 nm) for the composite oxides of Examples 1-3 and Comparative Example 1. In the figure, the dashed lines R1 and R2 are reference points to make it easier to visually understand the horizontal axis positions of the Raman peaks P1 and P2 for each example, with a shift amount of 640 cm². -1 and shift amount 920 cm -1 This indicates the position. As shown in Figure 12, the Raman spectra of all composite oxides show a shift amount of 640 ± 10 cm⁻¹. -1 and 920±20 cm -1 Peaks were observed. These peaks are designated as Raman peaks P1 and P2, and their specific shift amounts (S1 and S2) are shown in Table 1 below. Table 1 also shows the difference in shift amounts S2-S1, and the empirical formula derived by combining ICP analysis and HAXPES measurement.

[0245] [Table 1]

[0246] As shown in Table 1, the general formula Li described above applies to all of Examples 1-7 and Comparative Example 1. a M b NbMo c O d We were able to synthesize a composite oxide having the composition represented by and containing a rhenium oxide-type block structure composed of an octahedral structure. For Examples 1-7, the shift difference S2-S1 in the Raman spectrum was 285 cm⁻¹. -1 That was the result. Therefore, it can be seen that many Schottky defects have been introduced. In contrast, in Comparative Example 1, the shift difference S2-S1 was 285 cm -1 It remained below that.

[0247] <Battery performance evaluation> Using the active material powders obtained in the above examples and comparative examples, electrodes were prepared as follows.

[0248] First, a slurry was prepared by dispersing 100 parts by mass of active material, 6 parts by mass of conductive agent, and 4 parts by mass of binder in a solvent. The active material used was the composite material powder obtained by the method described above. The conductive agent was a mixture of acetylene black, carbon nanotubes, and graphite. The binder was a mixture of carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR). Pure water was used as the solvent.

[0249] Next, the obtained slurry was applied to one side of the current collector, and the coating was dried to form an active material-containing layer. A 12 μm thick aluminum foil was used as the current collector. Then, the current collector and the active material-containing layer were pressed together to obtain an electrode. The electrode weight was 40 g / m². 2 That was the case.

[0250] A non-aqueous electrolyte was prepared as follows. A liquid non-aqueous electrolyte was obtained by dissolving the electrolyte salt in an organic solvent. LiPF6 was used as the electrolyte salt. The molar concentration of LiPF6 in the non-aqueous electrolyte was 1 mol / L. A mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) was used as the organic solvent. The volume ratio of EC to DEC was 1:2.

[0251] A three-electrode beaker cell was prepared using the electrode obtained by the method described above as the working electrode, metallic lithium foil as the counter electrode and reference electrode, and a non-aqueous electrolyte prepared by the method described above.

[0252] The cycle life performance and discharge rate performance of each fabricated cell were evaluated as follows. The evaluation temperature was 25°C, and the potential range was set to a lower limit potential of 0.7V (vs. Li / Li) relative to the lithium reference potential. + ), upper limit potential 3.0V (vs. Li / Li + Charge and discharge cycles were performed as follows: Charging was performed in constant current-constant voltage mode, and discharging was performed in constant current mode. Cycle life was evaluated by repeatedly performing charge and discharge cycles with a current value of 1C and calculating the retention rate of discharge capacity at the 1st and 30th cycles (cycle capacity retention rate (%) = [discharge capacity at 30th cycle / discharge capacity at 1st cycle] × 100%). Discharge rate performance was evaluated by fixing the charging current at 1C and measuring only the discharge current value, and calculating the retention rate of discharge capacity at 5C relative to discharge capacity at 0.2C (discharge rate capacity retention rate (%) = [5C discharge capacity / 0.2C discharge capacity] × 100%). The calculated capacity retention rates for each are summarized in Table 2 below.

[0253] [Table 2]

[0254] The composite oxide contained in the active material obtained in Examples 1-7 is the Li of the general formula described above. a M b NbMo c O d It is expressed as follows, and the shift difference S2-S1 in the Raman spectrum is 285 cm⁻¹.-1 While the above compounds corresponded to the above formula, the composite oxide obtained in Comparative Example 1, although satisfying the above general formula, did not satisfy the above shift difference S2-S1. As shown in Table 2, the active materials of Examples 1-7 showed higher rapid charge / discharge performance and cycle life performance compared to the composite oxide of Comparative Example 1.

[0255] In detail, regarding the cycle capacity retention rate, Examples 1-7 showed a tendency to improve as the number of defects increased compared to Comparative Example 1. This is thought to be due to the improved electronic conductivity resulting from the inclusion of defects in the structure, which allowed for the maintenance of the conductive path during cycling. On the other hand, between Examples 1-7, the shift difference S2-S1 increased, meaning that the discharge rate retention rate tended to decrease as the number of defects increased. This is thought to be due to the effect of inhibiting Li diffusion by including defects in the structure.

[0256] According to the one or more embodiments and examples described above, an active material containing a composite oxide is provided. The composite oxide has a crystal structure that includes an octahedral structure composed of oxygen and a metal element, and includes a rhenium oxide-type block structure in which the octahedral structure is formed by sharing vertices, and the general formula is Li a M b NbMo c O d It is expressed as follows: Here, M in the formula is one selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si. Each subscript in the formula satisfies the relationships 0≦a≦b+2+3c, 0≦b≦1.5, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50, respectively. In the micro-Raman spectroscopy spectrum at an excitation wavelength of 532 nm, it is 640±10 cm⁻¹. -1 The Raman shift amount S1 of the Raman peak P1, which originates from the Mo-O bond appearing at 920±20 cm, and -1 The difference S2-S1 between the Raman shift amount S2 and the Raman peak P2, which originates from the Nb-O bond, is 285 cm⁻¹. -1This concludes the explanation. The active material described above can provide electrodes that enable the realization of a secondary battery with excellent rapid charge / discharge performance and cycle life performance, a secondary battery and battery pack with excellent rapid charge / discharge performance and cycle life performance, and a vehicle equipped with the battery pack.

[0257] Several embodiments of the present invention are described below.

[0258] [1] A crystal structure comprising an octahedral structure composed of oxygen and a metal element, and comprising a rhenium oxide-type block structure formed by the octahedral structure sharing vertices, General formula Li a M b NbMo c O d It is expressed as such, where M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, and includes a composite oxide with 0≦a≦b+2+3c, 0≦b≦1.4, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50. In the micro-Raman spectrum of the aforementioned composite oxide at an excitation wavelength of 532 nm, 640 ± 10 cm⁻¹ was observed. -1 The shift amount S1 of the Raman peak P1 originating from the Mo-O bond located at 920±20 cm -1 The difference between the shift amount S2 of the Raman peak P2, which originates from the Nb-O bond located at 285 cm⁻¹, and the shift amount S2 is 285 cm⁻¹. -1 That concludes the description of the active material. [2] A crystal structure comprising an octahedral structure composed of oxygen and a metal element, and comprising a rhenium oxide-type block structure in which the octahedral structure is formed by sharing vertices, General formula Li a M b NbMo c O dIt is expressed as such, where M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, and includes a composite oxide with 0≦a≦b+2+3c, 0≦b≦1.5, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50. In the micro-Raman spectrum of the aforementioned composite oxide at an excitation wavelength of 532 nm, 640 ± 10 cm⁻¹ was observed. -1 The shift amount S1 of the Raman peak P1 originating from the Mo-O bond located at 920±20 cm -1 The difference between the shift amount S2 of the Raman peak P2, which originates from the Nb-O bond located at 285 cm⁻¹, and the shift amount S2 is 285 cm⁻¹. -1 That concludes the description of the active material.

[0259] [3] The active material according to [1] or [2], wherein the crystal structure includes a plurality of rhenium oxide type blocks of different sizes, and the rhenium oxide type blocks are connected at least by octahedral edge sharing without periodicity.

[0260] [4] An electrode containing the active material described in any one of [1] to [3].

[0261] [5] The electrode according to [4], comprising an active material-containing layer containing the active material.

[0262] [6] Positive electrode and, The negative electrode and, Electrolytes and A secondary battery comprising, A secondary battery in which the positive electrode or the negative electrode is the electrode described in [4] or [5].

[0263] A battery pack comprising the rechargeable batteries described in [7] and [6].

[0264] [8] External terminals for power supply, Protection circuit and The battery pack described in [7] further comprises the following:

[0265] [9] comprising a plurality of the aforementioned secondary batteries, The battery pack according to [7] or [8], wherein the secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel.

[0266] A vehicle equipped with a battery pack as described in any one of

[10] [7] through [9].

[0267]

[11] The vehicle according to

[10] , which includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

[0268] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0269] 1... Electrode group, 2... Exterior member, 3... Negative electrode, 3a... Negative electrode current collector, 3b... Negative electrode active material containing layer, 4... Separator, 5... Positive electrode, 5a... Positive electrode current collector, 5b... Positive electrode active material containing layer, 6... Negative electrode terminal , 7... Positive electrode terminal, 10... Crystal structure, 10a... Octahedron, 10b... Tetrahedron, 11... Crystal structure, 11a... Octahedron, 11b... Tetrahedron, 18... Metal element, 19... Oxygen element, 21... Bus bar ,22…Positive lead, 23…Negative lead, 24…Adhesive tape, 31…Housing container, 32…Lid, 33…Protective sheet, 34…Printed circuit board, 35…Wiring, 40…Vehicle body, 41…Vehicle power supply, 42…Electrical control device, 43…External terminals, 44…Inverter, 45…Drive motor, 100…Secondary battery, 200…Battery pack, 200a…Battery pack, 200b…Battery pack, 200c…Battery pack, 300…Battery pack, 300a…Battery pack, 300b…Battery pack, 300c…Battery pack, 301a…Battery pack monitoring device, 301b…Battery pack monitoring device, 301c…Battery pack monitoring device, 342…Positive connector, 343…Negative connector, 345…Thermistor, 346…Protection circuit, 342a…Wiring, 343a…Wiring, 350…External for power supply Terminals, 352...positive terminal, 353...negative terminal, 348a...positive wiring, 348b...negative wiring, 400...vehicle, 411...battery management device, 412...communication bus, 413...positive terminal, 414...negative terminal, 415...switch device, 416...current detection unit, 417...negative input terminal, 418...positive input terminal, L1...connection line, L2...connection line, W...drive wheel.

Claims

1. The crystal structure includes an octahedral structure composed of oxygen and a metal element, and also includes a rhenium oxide-type block structure in which the octahedral structure is formed by sharing vertices. General formula Li a M b NbMo c O d It is expressed as such, where M is one or more selected from the group consisting of Ti, Zr, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, Cr, W, B, Mg, Al, Ca, Y, and Si, and includes a composite oxide with 0 ≤ a ≤ b + 2 + 3c, 0 < b ≤ 1.5, 0 < c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.

50. In the micro-Raman spectrum of the aforementioned composite oxide at an excitation wavelength of 532 nm, 640 ± 10 cm⁻¹ was observed. -1 The shift amount S1 of the Raman peak P1 originating from the Mo-O bond located at 920±20 cm -1 The difference between the shift amount S2 of the Raman peak P2, which originates from the Nb-O bond located at 285 cm⁻¹, and the shift amount S2 is 285 cm⁻¹. -1 Active material with a value of 294 cm⁻¹ or less.

2. The active material according to claim 1, wherein the crystal structure includes a plurality of rhenium oxide type blocks of different sizes, and the rhenium oxide type blocks are connected at least by octahedral edge sharing without periodicity.

3. An electrode comprising the active material according to claim 1 or 2.

4. The electrode according to claim 3, comprising an active material-containing layer containing the aforementioned active material.

5. Positive electrode and, The negative electrode and, Electrolytes and A secondary battery comprising, A secondary battery wherein the positive electrode or the negative electrode is the electrode described in claim 3.

6. A battery pack comprising the secondary battery described in claim 5.

7. External terminals for power supply, Protection circuit and The battery pack according to claim 6, further comprising the above.

8. The device comprises multiple secondary batteries, The battery pack according to claim 6, wherein the secondary batteries are electrically connected in series, parallel, or a combination of series and parallel.

9. A vehicle comprising the battery pack described in claim 6.

10. The vehicle according to claim 9, comprising a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

Images